Page 50 - My FlipBook

gingival wall partly flattened, but was left by this instru-
ment too much rounded at the bucco-gingival and linguo-
gingival angles. These angles were squared out Avith a small
fissure burr and the enamel hatchets. An inverted cone burr,
about one millimeter in diameter, was started in the distal
portion of the cavity and a cut made through the enamel
along the mesial groove into the principal fossa of the oc-
clusal surface. The enamel was chipped from either side of
this with chisel 15 and the groove or step broadened with
the burr, forming a flat pulpal wall. The buccal groove was
cut out to the crest of the buccal marginal ridge with the
same burr and the enamel wall trimmed to form with th<"
chisel, and the form of the step made retentive. A littU
softened material remained in the deeper portion of the
cavity, which was removed with spoon 20-9-12, and as a con-
venience in starting the filling a slight pit was cut with a
very small inverted cone burr in the axio-gingivo-lingual and
axio-gingivo-buccal angles, and a groove extended a short
distance occlusally along the axio-lingual and axio-buccal
angles with the same instrument.
The enamel wall was planed smooth with the chisel
and its form corrected, and the cavo-surface angle slightly
beveled in all its parts with the chisels and gingival margin
trimmers, thus completing the formation of the cavity. After
a thorough sweeping with punk held in the pliers for the
lemoval of the last traces of dust from. the walls, it was ready
lor filling.

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